Thermal vs updraft

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evapilotaz

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So I was happy flying along and all of a sudden I was in a 1000fpm :goofy:climb.:goofy:

It was breezy and maybe about 85 degree out.

I throttle back and adjusted trim to level flight. Once it was over I throttle up and readjusted my trim. It kind of caught me of guard.

Is this an updraft or a thermal? How would I know the difference
 
MAKG1 said:
What's the difference?

All weather is thermal.
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Hard to argue that.

But, given that things were long lasting enough for you to trim it out to a new airspeed and all, it could have been wave lift. Winds downstream of a mountain forming a standing wave with possibly lenticular cloud forms. The difference is 'was it turbulent or was it smooth'? Thermal lift is turbulent, wave lilft is smooth.
 
Bill Watson said:
Hard to argue that.

But, given that things were long lasting enough for you to trim it out to a new airspeed and all, it could have been wave lift. Winds downstream of a mountain forming a standing wave with possibly lenticular cloud forms. The difference is 'was it turbulent or was it smooth'? Thermal lift is turbulent, wave lilft is smooth.
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:yes::yes::yes:..:thumbsup:
 
My vote is thermals. You live in the desert after all.


Whoa! I just hit 18,000 posts. :happydance:
 
my experience is more from mountain turbulence than thermal. No fancy wave, just rotors off of 20,000' rocks. The updraft in the 2000fpm+ range gives you a lift and is usually followed by a drop when you hit a column of air going down at about the same velocity. Entry into an updraft can be abrupt. The seam between up and down can be even worse. Going up at that rate in a Va level cruise is odd but you know what's coming. When you're going down at a rate that's pegged your VSI and there's nothing you can do to arrest it? That gets a little tense, depending on how high you are. The air in the vicinity of the drafts I'm describing is bumpy. Like riding a clothes pin in an agitating washing machine. Especially flying out of a downdraft. Tail turbulence. I don't prefer it.


FYI, I've always liked this paper. http://pilotoutlook.com/aviation_weather/turbulence
 
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Had that happen last year. Was sight seeing over the Mississippi with the AP engaged and the eyes / camera mostly outside the cockpit. Something sounded a little different and I looked down to find myself well into the yellow arc (160kts and still accelerating). Totally unexpected, but then again lift changes between land and water ..
 
I frankly don't see a "difference." An updraft is simply an upward flow of air. It might be produced by various things, one of which is a "thermal." If you shoot up 1000' in 30 seconds while configured for level flight, it's an updraft, even if the reason is a thermal.
 
A thermal is a funnel that is drifting with the wind or it can even be somewhat stationary. A thermal can be quite useful to a glider but not so much if your trying to get somewhere.

Wave lift can sometimes be utilized like a tailwind. If you can visualize the winds aloft and terrain that are interacting you maybe able to stay in the lift zone for a period of time.
 
I would go for a thermal encounter.
 
I've always thought of "thermals" being related to solar heating and cloud formation, while "updraft" is what happens inside cloud layers related to storm building. I've found updrafts where I went from level to 1500 fpm climb despite reduced throttle and 10* nose down; it took me from 7000 to 9600 msl faster than I could get a block clearance.

Orographic lifting is just like ripples on the water after going over rocks, just proves you're downwind of some big hills. Mountain wave, in my Appalachian experience, alternately lifts you up and pushes you down.
 
Yeah, noticed it today bigtime. We were flying along level with some decent chop around 6000' and I'm fighting the thing level (no altitude hold!)... one minute forcing the thing down and building up speed and the next minute in a full on climb just to hold altitude. Crazy! Not used to this warm air flying!
 
On the upwind side?

Low altitudes, winds and mountains combined can make for a lot of ridge lift.

Unstable air makes mountain waves unlikely, but you can still get ridge lift. The downwind side will be VERY rough, even above the peaks.

Just with our local 15 knot winds at altitude, I've been getting a few hundred FPM smooth ridge lift and sink at 6000 over 2000-3000 foot mountains. You really notice that stuff in instrument training.

My favorite ridge story (which I think was actually a mountain wave) resulted in a 500 FPM climb at Vno in a 172N. Just popping over 2000 foot mountains for sightseeing.
 
Depends on where you were:
 

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CharlieTango said:
A thermal is a funnel that is drifting with the wind or it can even be somewhat stationary. A thermal can be quite useful to a glider but not so much if your trying to get somewhere.



Wave lift can sometimes be utilized like a tailwind. If you can visualize the winds aloft and terrain that are interacting you maybe able to stay in the lift zone for a period of time.
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Climbing out of Salida a few weeks back, I wanted to go out of the valley direct to the northeast but figured I'd have to circle for too long to do it, and planned a more typical downriver and around the mountain range departure.

Found a lovely thermal and rolled the airplane into a bank and started the process learned many years ago flying gliders to find the center of lift, and up we went. Theee and a half turns around, I had plenty of altitude to proceed direct northeast on course.

I was trying to "get somewhere" and the thermal assisted by cutting the drive time around the ridge from about 40 minutes to a 5 minute circle over the river-bend (and a tree, which was a nice turn about a point visual target), where the thermal was sitting.

Up in the rocks, I'll take whatever lift I can find. Being on the downwind side of a valley of canyon up against the rocks often yields a nice orographic lift that speeds the trip up.
 
evapilotaz said:
all of a sudden I was in a 1000fpm climb.

I throttle back and adjusted trim to level flight. Once it was over I throttle up and readjusted my trim. It kind of caught me of guard.
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If you were VFR you should have pitched the nose up and take all the free climb available.

And the trim...............you don't "trim" to adjust to level flight. That you do that with elevator. You "trim" to relieve control pressures.

No wonder you were troubled.
 
denverpilot said:
Found a lovely thermal and rolled the airplane into a bank and started the process learned many years ago flying gliders to find the center of lift, and up we went.
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It's been years since I flew a hang glider, but's there's nothing like punching into a big one and riding it up 3,000 feet or more.
 
kgruber said:
If you were VFR you should have pitched the nose up and take all the free climb available.

And the trim...............you don't "trim" to adjust to level flight. That you do that with elevator. You "trim" to relieve control pressures.

No wonder you were troubled.
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Good grief I knew some one was going to critized me.

I wanted to maintain my current altitude and speed. Maybe my process was all wrong. I'm still under 200 hrs so I'm learning.

When I saw the vsi jump up to 1000fpm I pushed the nose to level throttled back some and trimmed.

First encounter with something like that. Look at my sig I have a huge gap in my flying experience.
 
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You didn't do anything wrong.

Personally I probably would have taken the extra speed and held the altitude as long as it wasn't turbulent.

But it's your airplane, fly it how you want to.

Extra energy from the big old in contained nuclear reactor in the sky can often be harnessed into something useful.
 
midlifeflyer said:
I frankly don't see a "difference." An updraft is simply an upward flow of air. It might be produced by various things, one of which is a "thermal." If you shoot up 1000' in 30 seconds while configured for level flight, it's an updraft, even if the reason is a thermal.
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It can make a difference if you want to get out of it sooner rather than later...or stay in it longer rather than sooner. Often you can 'see' what's causing it if you understand it (by cloud types, location, characteristics) and fly according to whether you want more or less of it. The more you 'get' the difference, the more you can do.
kgruber said:
If you were VFR you should have pitched the nose up and take all the free climb available.
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That's the more efficient way to handle it though passengers may disapprove. While the altitude versus speed tradeoff may seem close to even, spending more time in 'up' air (and less in 'down' air) will provide greater cross country efficiency.
evapilotaz said:
Good grief I knew some one was going to critized me.

I wanted to maintain my current altitude and speed. Maybe my process was all wrong. I'm still under 200 hrs so I'm learning.

When I saw the vsi jump up to 1000fpm I pushed the nose to level throttled back some and trimmed.

First encounter with something like that. Look at my sig I have a huge gap in my flying experience.
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That was all fine - many ways to deal with it.
denverpilot said:
Personally I probably would have taken the extra speed and held the altitude as long as it wasn't turbulent.

Extra energy from the big old in contained nuclear reactor in the sky can often be harnessed into something useful.
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Especially in a sailplane.

I've finally stopped dolphin flying my airplane and settled down to fly it like what it is. Flying IFR pretty much limits one to enjoying the speed and holding the altitude at best.

However, what the OP did by adjusting the power and pitch to maintain speed and altitude would be exactly the correct thing to do in IFR terms, say what you are doing and do what you say. Well done and great practice!
 
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